Electrical apparatus



July 15, 1930. c. w. WY MAN ELECTRICAL APPARATUS F iled June 20, 1927Patented July 15, 1930 UNITED STATES PATENT OFFICE CHARLES W; WYMAN, OFCLAREMONT, NEW HAMPSHIRE, ASSIGNOR TO SULLIVAN v MACHINERY COMPANY, ACORPORATION OF MASSACHUSETTS ELECTRICAL APPARATUS Application filed June20,

My invention relates to electrical apparatus and more particularly toflame proof connections between a wall of the motor compartment and aconductor leading into the compartment.

An object of my invention is to provide an improvement in a miningmachine and more specifically an improved flame proof connection betweenthe walls of the motor section and a conductor passing therethrough.Another object is to provide an improved removable bushing between thewall of a compartment and a conductor leading into the same having meansto permit removal of the bushing and conductor from outside thecompartment. These and other objects and advantages will, however,subsequently more fully appear.

In the accompanying drawings I have shown for purposes of illustrationone form which my invention may assume in practice. In these drawings,-

Fig. 1 is a view partly in section and partly in elevation, of parts ofa mining machine having my invention embodied therein.

Fig. 2 is a detail sectional view of one of the flame proof bushings inoperative position and a conductor passing therethrough.

Fig. 3 is a fragmentary sectional view of the parts shown in Fig. 2indicating the manner in which the bushing and conductor are removedfrom the com artment.

In this illustrative orm of the invention my improved flame roofconnection is shown associated with a mining machine of the typedisclosed in a copending application to one Morris P. Holmes, Ser. No.136,446, filed Sept. 20, 1926. As shown in Fig. 1 the numeral 4indicates the motor section of the mining machine, and 5 the feed orcontrol section. The cutter carrying section has nothing to do with thepresent invention and accordingly has not been illustrated in thedrawings. The motor section 4 has in addition to the motor, a controllerhoused thereby, which controller is operated by a shaft 6 and a handle 7through an intermediate flexible connection 8. Power is conducted intothe motor compartment from a supply cable 9 by a connector plug 10supported in the feed section and by 1927. Serial No. 200,268.

the power carrying wires 11. These wires 11 pass through apertures 12and 13 in the abutting walls of the feed section and motor sectionrespectively and have at their ends,

means for connection to the controller which in this instance take theform of grommets 14. Either of the apertures 12 and 13 may be providedwith screw threads for receiving externally threaded bushings 15, eachof said bushings having a bore 16 therethrough for receiving one of thepower conducting wires leading into the motor compartment. It will benoted that the bores in these bushings are of a size to closely fit theconductors 11 over a relatively large area, thereby insuring that thejoint between the conductor and bushing is flame proof. Bushings 15 areof insulating material.

Fig. 3 illustrates the operation of removing one of the conductors 11and its attached grommet 14 through the apertures 12 and 13, and forthis purpose it will be noted that the apertures and bushing 15 are madesufficiently large to allow free passage of one of the grommetstherethrough. It is a well known fact that a screw threaded joint isvery effective in preventing the passage of flame for quite obviousreasons. It is also well known that any two surfaces in direct contactover a relatively wide area form a joint which is very effective inpreventing the passage of a flame, since it would be cooled andextinguished by contact with said surfaces.

As a result of my invention, it will be observed that improved meanshave been provided for preventing the transmission of a flame to theoutside of the motor compartment in the event of an explosion therein.Also it will be observed that with my improved one piece bushing theconductors may be removed from the motor compartment through theapertures 12 and 13 which avoids the delay and expense incident to theremoval of the old type of bushings and conductor where it was necessaryto get into the motor compartment and remove the grommets from the powerconducting wires.

While I have in this application specifically described one form whichmy invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration and that theinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claim.

What- I claim as new and desire to secure by Letters Patent is:

In a flame proof apparatus, a casing having a hole in the wall thereofand adapted to house an electrical device, means for making anelectrical connection with a device enclosed in said casing comprising aflexible cable passing through the hole in the Wall of the casing and agrommet on the end of said cable Within said casing and of a size thatwill just pass through said opening and a comparatively long cylindricalbushing surrounding said cable and threaded from the outside of saideasing into said opening to provide a flame proof joint between thecable and casing.

In testimony whereof I affix my signature.

CHARLES W. WYMAN.

